This invention relates in general to a process for coating seamed belts and more specifically to a process for coating belt seams with coatings containing film forming polymers.
Various techniques have been devised for joining belts such as photoreceptor belts. Belts may be joined in manufacture by overlapping the edge of one end of a sheet over the other opposite edge of the sheet thus forming a lap joint or seamed region that is thereafter welded. The technique of joining thermoplastic belted materials is well known and illustrated, for example, in U.S. Pat. No. 4,838,964 and U.S. Pat. No. 4,959,109, both of these patents being incorporated by reference herein in their entirety.
Acceptable joints formed in the aforementioned joining process for belt shaped electrophotographic imaging members perform satisfactorily when transported around relatively large diameter rollers. The lap joints or seams of these belts contain a deposit of web material melted during joining. These deposits or "weld splashes" are formed on each side of the welded web adjacent to and adhering to each end of the original web and to the regions of the web underlying each splash. Unfortunately, when the belts are transported around very small diameter rollers having, for example a diameter of about 19 mm or less, the weld splash on the outer surface of the belt gradually separates from the upper end of the photoreceptor web during cycling to form an open crevasse or crack. If the photoreceptor is cycled such that the cleaning blade is incident from the direction of the lower overlapped level, an abrupt or impulsive force can be delivered by the blade to the seam edge which can separate or cause further separation of the photoreceptor web and splash. Carrier beads and toner particles or liquid ink developer collect in the space between the web and splash and are periodically ejected when the splash flops open when, for example, passing around small diameter rollers. The ejected materials float to various subassemblies (e.g. corotrons, lamps) and causes them to fail or perform poorly and ultimately cause copy defects. Collisions of the blade with the irregular seam surface or with the flopping splash can also result in the blade becoming chipped and pitted. These chips and pits in the blade leave streaks of toner or liquid ink on the photoreceptor surface which eventually appear as streaks on copies made during subsequent electrophotographic imaging cycles and adversely affect image quality.
Thus, problems encountered with belt-type photoreceptors having a seam include repeated striking of the seam by cleaning blades. This causes toner developer or liquid ink agglomerates to form that are trapped at the irregular surface of the seam. Belted photoreceptors can also tend to delaminate at the seam when the seam is subjected to constant battering by the cleaning blade. Plus, collisions between the cleaning blade and an irregular seam surface can damage the blade thereby shortening blade and photoreceptor life and degrading copy quality.
If a photoreceptor seam is coated with a solution of a resinous coating material dissolved in a solvent which also dissolves or otherwise adversely interacts with the outer photoreceptor material, and heated or placed in a vacuum to accelerate the removal of the solvent, the incipient photoreceptor seam coating can undergo substantial redistribution and deformation resulting, for example, in non-uniform defects such as creasing, wrinkling, cracking, blisters and the like due to solvent attack of components in the photoreceptor. Moreover, during the use of such solution based coating techniques, the solvent can attack one or more layers of the photoreceptor belt and cause significant damage or complete destruction of the functional properties of the photoreceptor belt such as the flexibility, structural strength, or the imaging characteristics of the belt.